Light projection device



May 7, 1957 K. R. DEAN LIGHT PROJECTION DEVICE Filed OQL 21, 1954 lr wentor: Kehneth R. Dean,

LIGHT PROJECTION DEVICE 7 Kenneth R. Dean, Mercer Island, Wash., assignor to General Electric Company, a corporation of New York Application October 21, 1954, Serial No. 463,764

8 Claims. (Cl. 313-115) This invention relates in general to light projection devices and more particularly to a combination airplane landing and taxiing headlight for selectively projecting either a landing beam or a taxiing beam. Still more particularly, the invention relates to an electric incandescent lamp suitable for such purpose and to a mountconstruction therefor.

On many types of airplanes, it is common practice to provide the airplane with light-projection means for producing either a landing beam for use when the airplane is making a landing, or a taxiing beam for use when the airplane is taxiing about the air field. Heretofore, the landing and taxiing beams have been provided by separate light-projection devices or lamps mounted on the airplane. However, because of space limitation on certain types of airplanes, and also in view of the desirability of reducing the number and weight of parts, a need has developed for a combination landing and taxiing headlight or lamp which will operate to selectively project either a landing beam or a taxiing beam, at the choosing of the pilot. Generally, such landing beams are in the form of a narrow spot beam of the order of 500,000 maximum beam candlepower or so, while the taxiing beams are in the form of a relatively wide flood beam of the order of 50,000 maximum beam candlepower or It is an object of my invention, therefore, to provide a light-projection device for airplanes which is capable of selectively projecting either a landing beam or a taxiing beam conforming, in general, to the above-mentioned requirements therefor and substantially free of dark areas or voids.

Another object of my invention is to provide a combination airplane landing and taxiing incandescent lamp which is selectively operable to produce either a landing or a taxiing beam of the above-mentioned general character and substantially free of dark areas or voids.

Still another object of my invention is to provide a mount construction for such a combination airplane landing and taxiing lamp.

Briefly stated, in accordance with one aspect of my invention, a relatively high wattage main or landing beam filament in the form of a linear coil disposed axially of and approximately at the focus of an approximately paraboloidal reflector, is connected in series with a pair of alike supplementary linear coil filaments which are of materially lower wattage than the main filament and are disposed on opposite sides of and closely adjacent the main filament in a position extending transversely of the reflector axis and with their axes approximately coaligned and intersecting the focus of the reflector. Current connections are provided to the respective filaments to enable the selective operation either of the main filament alone to provide a landing beam, or of the three filaments in series to provide a taxiing beam.

Further objects and advantages of my invention will appear from the following detailed description of a species thereof and from the accompanying drawing.

nit ed States Patent 2,791,713 Patented May 7, 1957 In the drawing, Fig. 1 is a horizontal sectional view of an electric incandescent lamp according to my invention; and

Fig. 2 is a perspective view, on an enlarged scale, of the mount structure of the lamp.

Referring to the drawing, the invention is there shown as applied to a self-contained reflector-type incandescent lamp of the sealed beam type described and claimed in U. S. Patent 2,148,314, D. K. Wright, and comprising a sealed glass envelope or bulb 1 consisting of preformed pressed glass reflector and cover glass sections 2 and 3,

respectively, sealed together at their peripheries by fusion, as indicated at 4. The concave inner surface 5 of the reflector section 2 is formed of approximately paraboloidal shape and is covered with a reflecting coating 6 of aluminum, silver or other similar light-reflective material.

Mounted on the rear outer side of the reflector section 2 at the region of the apex or center thereof is a base structure 7 of the general type shown and described in U. S. Patent 2,272,512, Cotman, and comprising a plurality (3) of terminal contacts 8 in the form of metal straps or lugs which are suitably fastened, as by soldering for instance, to the closed nippled ends 9 of respective metal ferrules or thimbles 10. The contact lugs 8 are provided with screw terminals 11 for connecting current supply wires thereto.

the glass of the reflector section 2 and they are provided with skirt portions 12 which are feathered to knife edges embedded and fused in the glass of the reflector section 2 around respective openings or passageways 13 through the wall thereof. The thimbles 10 are preferably arranged in a symmetrical triangular manner on the rear side of the reflector section 2, with each thimble located approximately the same distance from the reflector axis and with two of the thimbles disposed in an axial plane of the reflector section. The envelope 1 is provided with an exhaust tubulation 14 communicating with the interior of the envelope through an exhaust aperture 15 in' the envelope wall at the apex of the reflector section 2. After exhaustion of the envelope through the tubulation 14 and, if desired, introduction of a suitable gas filling Mounted within the envelope-1 and supported solely from the metal ferrules 10 in spaced relation to the envelope wall is a lamp mount structure 17 according to the invention and comprising a plurality (3) of rigid lead-in conductors or inleads 18, 19 and 20 suit-ably secured at their outermost ends within the nipples 9 of respective ferrules 10, as by solder 21 as shown. From the ferrules 10, the lead-in conductors 18, 19 and 20 extend through the openings 13 in the wall of the reflector section 2 and into thev envelope 1 in more or less parallel spaced relation. Two of the lead-in conductors, i. e., the two lead-in conductors 18 and 19 which are disposed in an axial plane of the reflector section, are connected at their innermost ends to the opposite ends of a main or landing beam filament 22 preferably in the form of a linear coiled-coil wire of tungsten or other suitable refractory metal. For the purposes of the invention, the main filament 22 is of relatively high wattage, for example around 600 watts, with a rated voltage of around 28 volts. The filament 22 is supported on the conductors 18, 19 in a position symmetrically disposed with respect to the focus of the reflector section'zand with the axis of the coil co-aligned with the axis of the reflector section. The filament 22 is formed with straight, i. e., uncoiled, end leg portions 23 extending laterally of the coil and across the conductors 18, 19, and they are pro-.

vided with tight-fitting tungsten wire slip-over coils 24' The ferrules 10 are formed of a suitable metal which will readily wet and adhere to which are welded to the respective conductors 18, 19 to thereby form the filament connections or joints. If desired, the filament joints may be provided with heatdissipating means which, as shown, may be of the type disclosed and. claimed in UL 8'. Patent 2,366,292, Smith, and comprising thin sheet metal plates 25' of a suitable metal, such as iron for instance, which extend along and are weldedor otherwise suitably fastened to the rwpective lead-in; conductors 18, 19 so as to overlie and engage the coilencl'osed. filament end legs 23 at points opposite their welded connections to the conductors 18, 19. To rigidity the mount structure 17' and maintain the leadfin conductors 13, 1.9 and 20 in fixed relation to each other, suitable insulating bridges 26, 27 and 28 are. connected. acrossrespective pairs of the lead-in conductois to insulatively and rigidly tie them together, as shown. T '.c said bridges each comprise a glass rod 29 having a pair of support wires 30. embedded in each end thereof-and welded to the adjacent lead-in conductor.

In accordance with the invention, a pair of supplementary or side. filaments 31 and 32, ot materially lower wattage and voltage rating than the main filament 22, are provided on. opposite sides of and closely adjacent the main filament. The supplementary filaments 31 and 32 are. preferably in the form of linear coils of tungsten wire, and they are disposed with their coil axes approximately normal to the reflector axis and approximately coali'gned and intersecting the focus of the reflecting surface 6. Also as shown, the supplementary filaments 31 and'32 are preferably disposed approximately in the same axial plane of the reflector section 2 as the two lead-in conductors 18 and 19 for the main filament. For the purposes of the invention, the supplementary filaments 31 and 32 should have a. voltage rating ranging approximately from 20 to 30 percent (preferably about one-fourth) the corresponding voltage rating of the main. filament. The wattage rating of the supplementary filaments 31 and 32 is dependent upon their voltage rating and upon the corresponding wattage and voltage ratings of the main filament. Thus, the wattage rating. of the supplementary filaments will vary between to 18 percent of the corresponding wattage rating of the main filament, as the voltage rating of. the supplementary filaments varies between to 30 percent, respectively, of the correspond.- ing voltage rating of the main filament. For the preferred. voltage rating of the supplementary filaments of about one-fourththe corresponding voltage rating. of the main filament, the wattage rating of the supplementary filaments will be about one-sixth the corresponding. wattage rating of the main filament. filament 22 is of the particular wattage and voltage rating specified hereinabove, i. e., 600 watts at 28 volts, the supplementary filaments 31 and 32 are each designed to operate at approximately 100 watts and 7 volts.

In accordance with the invention, the supplementary filaments 31 and 32 are connected in series with the main filament 22. To this end, the inner ends of the supplementary filaments 31 and 32 are interconnected by a jumperwire or conductor 33' while the outer ends-of the supplementary filaments are connected one to the third lead-in. conductor 20 and the other to a spud wire 34 connected to one of the lead-in conductors 18, 19 for the main filament 22, e. g., to lead-in conductor 19 as shown. The jumper wire 33 is formed of rigid wire similar to that of the lead-in conductors 18, 19 and 20, and it is rigidly supported in place on the mount 17 in a suitable manner, as by a rigid support Wire 35 welded at one end to the jumper wire 33 and embedded at its other. end in the glass rod 29 of the insulative bridge 26.

To avoid. overheating of the jumper wire 33 by the main filament 22 during the operation of the lamp in that one of its two alternative mounting positions wherein the jumper wire is located above the main filament, the

said jumper wire 33 is formed. and mounted sees not to directly overlie the main filament. H To this end, the

Thus, where the main jumper wire 33 is formed of U shape, with its two legs spaced apart a distance greater than the over-all diameter of the coiled-coil main filament 22. The U-shaped jumper wire 33 is disposed in a plane more or less parallel to the plane of the two lead-in conductors 18 and 19 and it is mounted symmetrically with respect to the vertical axial plane of the reflector section 2 so as to locate each leg 36 of the U entirely to one side of the main filament 22 and'the base portion 37" of the U entirely to the rear of the rearward. end of the main filament, as shown in Fig. 1.

In use, the lamp according to the invention is connected' in. an operating. circuit which is, adapted to selectively connect either the main filament 22 alone, or the three filaments 22,31 and 32in series, across an electric power supply having a voltage corresponding to the rated operating voltage of the main filament 22, for example, 28. volts in the particular case set forth. When the line voltage is" impressed across the main filament 22 alone, a high. intensity relatively narrow spot or landing beam is produced having a maximum beam candlepower ranging from 450,000 to 500,000 in the case of a 600 watt filament; When the line voltage is impressed across the three filaments 22, 31 and 32 in series, a relatively Wide flood or taxiing beam of the required lateral spread is produced having amaximum beam candlepower of the order of 50,000 and a smoothly graded intensity distribution whereby the beam is entirely free of dark areas or voids. In this t'zuiiingbeam, the main filament 22, operating. at a reduced voltage approximating one-half its" rated voltage, provides the central portion of thebeam while the two side' filaments 31 and 32 provide the wide spread light at either side of the taxiing beam.

, If the supplementary'fil'amerits 31 and 32 were of a rated voltage and wattage lower than the range of voltages and wattages specified hereinabove, then while a taxiing" beam would be produced of substantial lateral and vertical spread, nevertheless too much of the line voltage would be distributed across the main or landing beam filament 22 and not enough across the two supplementary filaments with the result that too high a candle power would be produced in the center of the taxiing beam and the beam would have pronounced dark spots or voids at either side of the center. However, by employing, in accordance with the invention, supplementary filaments 31'a'nd 32 of arated voltage and wattage such thattli'e line voltage is more or less evenly divided across the landing beam filament on the one hand and the pair ofsiipplementary' filaments on' the other hand when the three filaments are operated in series, then a better taxiing beam pattern is produced which not only is of the required spre'adcharacter'istics but'which also is character- .izedby a smoth and relatively uniform gradation in candle power distribution, substantially free of dark areas or voids;

It will be apparent from the above description that I have provided a combination airplane landing and taxiing lamp which not only will provide a concentrated high candle power (450,000 to 500,000 maximum beam candle power) spot beam suitable for airplane landing purposes, but which also will provide, at will, a widespread appreciably lower candle' power (i. e., approximately 510,000 maximum beam candlepower) beaniadmirably suitable for airplane taxiing purposes. Moreover, the arrangement of the several filaments in the lamp for providing the different type beams is such that both beams are. symmetricaland on the lamp axis. As a result, the lamp can be installed and operated, without adverse results, either in a right-side up or an upsidedown position on the airplane, with the two supplementary filaments 31 and 32 disposed horizontally, suchan alternative mounting being a highly desirable feature. Also, the particular construction of the mount 17 according to theinvention; in'cluding the use of a jumper. wire 33 ofthepjarticular form'disclosed located entirely to the side of the main filament 22 so as not to directly overlie the latter when the lamp is operated in that one of its two optional mounting positions wherein the jumper wire 33 is located above the main filament 22, assures a satisfactory operating life for the lamp in service.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A light projection device comprising a concave reflector member having a reflector surface of approximately paraboloidal shape, a light source comprising a main filament in the form of a linear coil disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector surface and a pair of supplementary filaments in the form of similar linear coils disposed on opposite sides of and closely adjacent said main filament with their axes approximately normal to the reflector axis and approximately co-aligned and intersecting the focus of said reflector surface, and current connection means connected to said main and supplementary filaments and including means interconnecting all of said filaments in series for selective independent operation of said main filament and series operation of all said filaments.

2. A light projection device substantially as set forth in claim 1 wherein the said supplementary filaments have approximately corresponding voltage ratings ranging approximately from 20 to 30 percent of the corresponding voltage rating of said main filament.

3. A light projection device substantially as set forth in claim 1 wherein the said supplementary filaments each have a voltage rating of approximately one-fourth the corresponding voltage rating of said main filament.

4. A light projection device comprising a concave reflector member having a reflector surface of approximately paraholoidal shape, a light source comprising a linear coiled-coil main filament disposed approximately coaxial with the axis of and approximately centered at the focus of said reflecting surface, said main filament having a wattage and voltage rating of the order of 600 watts and 28 volts, and a pair of supplementary linear coil filaments of similar form disposed on opposite sides of and closely adjacent said main filament with their axes approximately normal to the reflector axis and approximately co-aligned and intersecting the focus of said reflector surface, said supplementary filaments each having a wattage and voltage rating of approximately 100 watts and 7 volts, and current connection means connected to said main and supplementary filaments and including means interconnecting all of said filaments in series for selective independent operation of said main filament and series operation of all said filaments.

5. An electric incandescent lamp comprising a sealed envelope having an approximately paraboloidal reflector section and a light-transmitting window section, a light source mounted in said envelope and comprising a relatively high wattage main filament in the form of a linear coil disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector section and a pair of supplementary linear coil filaments disposed on opposite sides of and closely adjacent said main filament with their axes approximately normal to the reflector axis and approximately co-aligned and intersecting the focus of said reflector section, said supplementary filaments each having a voltage rating of the order of from 20 to 30 percent the voltage rating of said main filament, and current connection means comprising lead-in wires sealed into said envelope and connected to said filaments and including means interconnecting said filaments in series for selective independent operation of said main filament and series operation of all said filaments.

6. An electric incandescent lamp comprising a sealed envelope having an approximately parabololdal reflector section and a light-transmitting window section, and a mount sealed in said envelope and comprising a plurality of rigid lead-in conductors extending in spaced relation through and rigidly supported from the wall of said envelope, a relatively high wattage coiled-coil main filament disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector section and connected at its ends across a pair of said lead-in conductors, a pair of supplementary linear coil filaments disposed on opposite sides of and closely adjacent said main filament with their axes approximately normal to the reflector axis and approximately co-aligned and intersecting the focus of said reflector section, said supplementary filaments each having a voltage rating of the order of from 20 to 30 percent the voltage rating of said main filament, the outer ends of said supplementary filaments being respectively connected to one of the said pair of lead-in conductors and to a third one of said lead-in conductors, and a rigid jumper conductor connecting the inner ends of said supplementary filaments and insulatively supported on said mount.

7. An electric incandescent lamp as set forth in claim 6 wherein the said jumper conductor is of approximately U-shape and is disposed in a plane extending approximately parallel to the reflector axis and to said supplementary filaments and lying entirely to one side of said main filament, with the two legs of the U located on opposite sides of said main filament and the base portion of the U located entirely to the rear of the rearmost end of said main filament.

8. An electric incandescent lamp comprising a sealed envelope having an approximately paraboloidal reflector section and a light-transmitting section, and a mount sealed in said envelope and comprising a plurality of rigid lead-in conductors extending in spaced relation through and rigidly supported from the wall of said envelope, a pair of said lead-in conductors being disposed approximately in an axial plane of said reflector section, a relatively high wattage coiled-coil main filament disposed approximately coaxial with the axis of and approximately centered at the focus of said reflector section and connected at its ends across the said pair of lead-in conductors, a pair of supplementary linear coil filaments disposed approximately in the plane of said pair of lead-in conductors and on opposite sides of and closely adjacent said main filament with their axes approximately normal to the reflector axis and approximately co-aligned and intersecting the focus of said reflector section, said supplementary filaments each having a voltage of the order of from 20 to 30 percent the voltage of said main filament, the outer ends of said supplementary filaments being respectively connected to one of the said pair of lead-in conductors and to a third one of said lead-in conductors, and a rigid jumper conductor connecting the inner ends of said supplementary filaments and insulatively supported on said mount, said jumper conductor being of approximately U shape and being disposed approximately symmetrical with respect to the vertical axial plane of the reflector section and in a plane approximately parallel to the plane of said pair of lead-in conductors, with the base of the U located entirely to the rear of the rearmost end of said main filament.

References Cited in the file of this patent UNITED STATES PATENTS 2,317,031 Cotman et al Apr. 20, 1943 

